The described subject matter relates generally to turbine engines, and more specifically to internally cooled airfoils for turbine engines.
Gas turbine engines are known and when used on aircraft typically include a fan delivering air into a bypass duct and into a compressor section. Air from the compressor is passed downstream into a combustion section where it is mixed with fuel and ignited. Products of this combustion pass downstream over turbine rotors driving them to rotate.
With increases in compressor and turbine temperatures, it becomes more important to efficiently utilize the air that is delivered into the compressor while maintaining or increasing the useful life of turbine blades. One source of inefficiency is in the varying cooling requirements at different operating conditions. For example, cooling requirements at cruise and idle conditions are much lower than at high-power conditions. Some of the cooling requirements are of course naturally mediated by the lower compressor speed generating less cooling air. Other attempts have been made to provide thermally controlled valves to the cooling manifold. However, further mediation of cooling air would be useful to increase efficiency at low engine speeds such as cruise, while also potentially reducing tip clearance requirements.